Crossbow-type underwater gun comprising a stretching device

ABSTRACT

The present invention relates to a crossbow-type underwater gun having resilient propulsion means comprising at least two bungee type side resilient cords ( 8 ), the gun being characterized in that it includes a device for stretching said resilient cords ( 8 ) comprising:  
     a moving head piece ( 11 ) to which said first fixing elements ( 11   1 , 11 2 ) can be fixed, said head piece ( 11 ) being suitable for sliding along the front portion of said spear support element ( 2 ); and  
     a lever arm ( 10 ), said lever arm ( 10 ) co-operating with a rod ( 12 ) via a thrust and retaining device ( 13, 14, 23, 24 ):  
     in such a manner as to enable said resilient cords ( 8 ) to be stretched by performing a succession of pivoting actions of said lever arm ( 10 ) between an initial position (B 1 ) and a thrusted position (B 2 ).

[0001] The present invention relates to a crossbow-type underwater gun,i.e. having resilient side cords of the “bungee” type that are stretchedin order to propel the spear.

[0002] In conventional manner, such guns are constituted by a buttextended by a spear-carrier tube and provided with a trigger release.The tube supports a spear propulsion mechanism constituted by two sidebungees. The front ends of the bungees are fixed to a support piecewhich is disposed at the head end of the gun, and which also generallyserves as means for guiding the spear. The rear ends of the bungees areconnected together by a metal ring referred to as a “loop” for insertingin a notch formed in the rear portion of the spear, in order to propelthe spear after the bungees have been stretched.

[0003] Such guns are traditionally cocked by direct application of forceusing both arms, stretching the bungees towards the butt, and engagingthe loop in the notch in the spear. However, that operation requires alarge amount of force and is not possible for all individuals, inparticular with a high-power gun, i.e. a gun having a long spear-carriertube and possibly also a plurality of side bungees. Under suchcircumstances, the butt needs to be pressed against the abdomen.Furthermore, there is danger of injuring the fingers if the loop ispoorly engaged in a spear notch, or when releasing the bungees, not tomention the abdominal pain caused by pressure from the butt.

[0004] The object of the present invention is to provide a crossbow-typeunderwater gun provided with a stretching device that is simple,reliable, and enables any individual, even a relatively weak person, tocock the gun in complete safety.

[0005] To do this, the present invention provides a crossbow-typeunderwater gun comprising:

[0006] a butt having a mechanism for blocking the rear end of a spearand a member for unblocking said spear, preferably a trigger;

[0007] a longitudinal spear support element whose rear end is engaged insaid butt; and

[0008] resilient propulsion means comprising at least two bungee typeside resilient cords whose front ends are suitable for being fixed tofixing elements and whose rear ends are suitable for engaging in atleast one notch in the rear portion of said spear.

[0009] According to the invention, the gun includes a device forstretching said resilient cords, the device comprising:

[0010] a moving head piece to which said first fixing elements can befixed, said head piece being suitable for sliding along the frontportion of said spear support element between:

[0011] a rear position enabling said resilient cords to be engagedwithout tension in said notch; and

[0012] an advanced position in which said resilient cords are stretchedmaximally when they are engaged in said notch;

[0013] a rod, said moving head piece being suitable for sliding alongsaid spear support element by moving said rod in its longitudinaldirection, preferably parallel to that of said longitudinal spearsupport element; and

[0014] a lever arm, said lever arm co-operating with said rod via athrust and retaining device which makes the following possible:

[0015] moving said rod in said longitudinal direction under drive frompivoting said lever arm;

[0016] holding said rod in an advanced position corresponding to thetravel distance of said rod resulting from said pivoting of the leverarm, while said lever arm is returned to its initial position by beingpivoted in the opposite direction; and

[0017] thereby enabling said resilient cords to be stretched byperforming a succession of pivoting operations on said lever arm betweenan initial position and a thrusted position.

[0018] In a particular embodiment, said lever arm cooperates with atransverse pivot pin secured to said longitudinal spear support element,thus enabling said lever arm to pivot about said pin between:

[0019] a high initial position in which said arm is preferablysubstantially parallel to the rear portion of said longitudinal spearsupport element and beneath it; and

[0020] a low, thrusted position where said lever arm is in an inclinedor vertical position. The term “transverse” is used herein to mean adirection extending perpendicularly to said longitudinal direction.

[0021] In practice, said pivot pin for the lever arm is situatedsubstantially in the middle portion of the gun and is at the front endof said lever arm, which itself extends towards the rear end of the gunso that the lever arm can be pivoted downwards by being pusheddownwards.

[0022] In particularly advantageous manner, the thrust and retainingdevice is of the mechanical type and comprises:

[0023] a thrust piece having an orifice through which said rod passes,the orifice being of diameter substantially larger than the diameter ofsaid rod so that said thrust piece can pivot relative to the axis ofsaid rod between:

[0024] an off-axis, thrust and blocking position in which said thrustpiece is secured to said rod and can entrain it forwards in saidlongitudinal direction under drive from pivoting said lever arm; and

[0025] a return position in which said rod lies on the axis of saidfirst orifice, and said thrust piece can thus return freely to itsinitial position by moving rearwards in translation in said longitudinaldirection;

[0026] a retaining piece including an orifice through which said rodpasses, the orifice being substantially larger in diameter than said rodsuch that said retaining piece can pivot relative to the axis of the rodbetween:

[0027] an off-axis, retaining and blocking position in which saidretaining piece blocks the rod by preventing it from sliding rearwardsin said longitudinal direction; and

[0028] an unblocking position in which said rod can slide freely in saidlongitudinal direction; and

[0029] said retaining piece being held in said retaining and blockingposition while said thrust piece is in its return position, and saidretaining piece being held in said unblocking position while said rod issliding forwards in said longitudinal direction.

[0030] By actuating said retaining piece towards the unblockingposition, while the bungees are stretched and the spear is cocked, thegun is uncocked, said moving head piece being pulled rearwards by thebungees.

[0031] Preferably, said orifice of said first piece comprises an orificein the form of a tubular element, thus constituting a blocking bearingthat is more effective. Said thrust piece then includes a bottom plateon which it is possible to exert the action that leads to said tubularelement pivoting.

[0032] Advantageously, the underwater gun of the invention comprises thefollowing characteristics in which:

[0033] said lever arm is secured to said thrust piece, preferablysecured to a plate of said thrust piece, by means of a link in such amanner that pivoting said lever arm causes said thrust piece to pivot,said thrust piece occupying:

[0034] a said off-axis, blocking position when said lever arm pivotsfrom its said initial position towards its said thrusted position; and

[0035] a said return position when said lever arm pivots in the oppositedirection from its said thrusted position towards its said initialposition; and

[0036] said retaining piece is held in its said retaining position byresilient extender return means, preferably made of elastomer material,suitable for being compressed by pivoting of said retaining piecetowards said unblocking position.

[0037] The thrust retaining device thus requires only one resilientreturn means to be provided.

[0038] It is thus by means of an alternating bracing phenomenon of thetwo thrust and retaining pieces that are hinged on said rod secured tosaid moving head piece having the bungees fixed thereto that it ispossible for each operation on the lever arm to cause said thrust pieceto thrust against the rod while said retaining piece retains it.Operated using one arm only, the gun can be cocked without effort, ingeneral by a succession of 4 to 8 pivot operations.

[0039] In an embodiment, the gun presents the following characteristics,in which:

[0040] said retaining piece is L-shaped having a first plate and asecond plate forming a right angle at the bottom end of said firstplate;

[0041] said orifice of said retaining piece being in the top portion ofsaid first plate;

[0042] said resilient return means being in annular form around said rodin extension between a stationary stop element and said first plate;

[0043] said resilient return means exerting thrust on said first plate,pushing it into an inclined position corresponding to said retainingposition as obtained by blocking said retaining piece, the top end ofsaid first plate preferably being inclined towards the rear of said gun;and

[0044] said first plate being capable of being pivoted towards saidunblocking position for unblocking said retaining piece by moving saidrod forwards in said longitudinal direction and by pivoting said secondplate, preferably upwards, causing said resilient return means to becompressed in both cases so that said spear can be uncocked by exertingupward pressure using a finger on said second plate.

[0045] Said stationary stop element is secured to said longitudinalelement. Furthermore, it will be understood that when the rod advancesunder drive due to pivoting said lever arm, it compresses said resilientreturn means and unblocks said retaining piece.

[0046] In an embodiment, said gun includes a stationary baseplatesecured to said longitudinal spear support element, said baseplatesupporting said transverse pivot pin of said lever arm and the variouscomponent parts of said thrust and retaining device.

[0047] In particular, said butt contains said thrust pieces, saidretaining pieces, and the various other component elements of theretaining device such as said resilient return means and said stationarystop element.

[0048] More particularly, said baseplate comprises at least one, andpreferably at least two bottom orifice(s) through which said rod passes,and also preferably at least one top orifice through which saidlongitudinal spear support element constituting a spear-carrier tubepasses.

[0049] Said orifices of said baseplate also constitute blocking bearingswhen the longitudinal axis of said rod is in an off-axis position.

[0050] Advantageously, said moving head piece has a first orificethrough which said spear-carrier tube passes and a second orificethrough which said spear passes and which serves as guide meanstherefor, and a hollow housing in which said rod comes into abutment tocause said moving head piece to slide forwards.

[0051] The present invention also provides a stretching device useful inmaking a crossbow-type underwater gun of the invention, the stretchingdevice being characterized in that it comprises:

[0052] a said moving head piece; and

[0053] a said thrust and retaining piece comprising:

[0054] a said rod;

[0055] a said lever arm; and

[0056] preferably a said baseplate supporting said rod and said leverarm and said thrust piece and said retaining piece.

[0057] The stretching device may be supplied in the form of a kitsuitable for fitting to any crossbow-type underwater gun, that is notalready provided with a stretching device.

[0058] Other characteristics and advantages of the present inventionappear in the light of the following detailed description given withreference to the accompanying drawings, in which:

[0059] FIGS. 1 to 3 are side views of a gun of the present invention,FIG. 2 showing the gun in the uncocked position, FIG. 3 showing the gunin its cocked position, and FIG. 1 showing it in an intermediateposition;

[0060]FIG. 4A is a side view of the gun of the invention showing thebaseplate supporting the lever arm 10 and the rod 12, with a fragmentarylongitudinal section view of the thrust and retaining device;

[0061]FIG. 4B is a view in section on AA of FIG. 4A;

[0062]FIG. 5A is a side view of an embodiment of said lever arm;

[0063]FIG. 5B is a view of the underside of the FIG. 5A lever arm;

[0064]FIG. 6C is a section view on BB of FIG. 5A.

[0065]FIG. 6A is a side view of the moving piece 11 in which the movingrod 12 comes into abutment;

[0066]FIG. 6B is a plan view of the moving piece 11 of FIG. 6A; and

[0067]FIG. 6C is a section view of the moving piece 11 in section CC inFIG. 6B.

[0068] The crossbow-type underwater gun of the invention comprises abutt 1 with a trigger 4 and a locking mechanism (not shown) integratedin the butt 1 and suitable for retaining the rear end of the spear 3when it is put into place and engaged in the butt. Said trigger 4co-operates with said locking mechanism so as to enable the spear to bereleased and so as to cause it to be propelled when said trigger isactuated. A spear-carrier tube 2 is engaged in said butt 1, and thespear is placed on the spear-carrier tube 2.

[0069] A moving head piece 11 slides along said spear-carrier tube 2between a rear position (A1) towards which it comes into abutmentagainst a stationary baseplate 18, and an advanced position (A2) inwhich it comes into abutment against a front end stop 16 of thespear-carrier tube 2. The moving head piece 11 has a first orifice 25through which said spear-carrier tube 2 passes. However an embodimentcould be provided in which the moving piece 11 slides inside saidspear-carrier tube 2. The moving head piece 11 also has a top orifice 26through which said spear 3 passes, and which acts as guide meanstherefor.

[0070] Two bungee cords 8 placed above and on either side of thespear-carrier tube 2 are fixed at their front ends to first fixingelements 11 ₂, 11 ₁ which are secured to said moving piece 11, beingfixed by screw fastening in hollow side housings 6 ₁, 6 ₂ thereof. Therear ends of the bungees 8 are connected to each other via a catchelement 9 suitable for co-operating with one or more notches 17 in therear portion of the spear 3.

[0071] A loop-forming metal ring 9 connects together the rear ends ofthe bungees 8. The loop 9 is secured to the rear ends of the bungees 8by conventional screw cord means.

[0072] In order to cock the spear 3 on the gun, the following steps areperformed:

[0073] 1) the moving head piece 1 is moved rearwards (A1) by beingcaused to slide rearwards until the bungees can be engaged withouttension by means of said catch elements 9 penetrating into a said notch17; and

[0074] 2) the moving head piece 11 is caused to slide forwards (A2)until the bungees are maximally stretched, with this being done with thehelp of a series of means acting in combination with the moving piece 11to constitute a device for stretching the bungees 8.

[0075] The device for stretching the bungees 8 comprises, between saidmoving piece 11, a rod 12 extending parallel to the spear-carrier tube 2and beneath it in the embodiment shown in the figures, it beingunderstood that said moving rod 12 could be placed inside thespear-carrier 2 if the moving piece 11 is mounted to slide inside saidspear-carrier tube 2. The device for stretching the bungees 8 alsocomprises a lever arm 10. The rod 12 and the lever arm 10 are supportedby a stationary baseplate 18 secured to the middle portion of thespear-carrier tube 2. As shown in the figures, the baseplate 18 has acircular orifice through which said spear-carrier tube passes, and asecond orifice 29 lower down through which said rod 12 passes.

[0076] At one end, the lever arm 10 has two fork branches 10 ₁ and 10 ₂,said branches 10 ₁ and 10 ₂ having respective end orifices 7 ₁ and 7 ₂through which there passes the horizontal hinge pin 7 of said lever arm.The two branches 10 ₁ and 10 ₂ of the lever arm 10 are placed astridesaid baseplate 18 and said horizontal pin 7 passes through saidbaseplate 18 and said spear-carrier tube 2. The lever arm 10 presents agenerally semicylindrical hollow shape as shown in FIG. 5C enabling itto fit closely to the shape of the spear-carrier tube when it is foldedagainst the spear-carrier tube 2 by being pivoted upwards. The lever arm10 is extended rearwards over a length that varies depending on themodel of gun. Its length is also adapted to the variety of tube lengthsand depends on the power of the bungees. It can be made longer orshorter depending on the desired maximum force required for cocking thegun.

[0077] The baseplate 18 contains a thrust piece 13 comprising a tubularelement 13 ₁ through which said rod 12 passes, being significantlylarger in diameter than the rod 12, so that said tubular element 13 ₁can become off-centered relative to the longitudinal axis of said rod12. Said thrust piece 13 also has a piece 13 ₂ perpendicular to saidtubular element 13 ₁. Said perpendicular piece 13 ₂ is connected to saidlever arm 10 via a link 23, such that pivoting said lever arm 10 from ahigh position (B1) parallel to said spear-carrier tube 2 to a low,thrusted position (B2) that is inclined or vertical relative to saidspear-carrier tube 2, blocks said tubular element 13 ₁ against said rod12 and entrains it longitudinally towards the front. The front end ofthe rod 12 co-operates with a bottom hollow housing 27 in said movingpiece 11, causing it to move longitudinally in sliding.

[0078] The rod 12 can be secured to the moving piece 11 in said hollowhousing 27.

[0079] When said lever arm is caused to pivot in the opposite directionfrom its said low, thrusted position (B2) towards its initial, highposition (B1) parallel to said spear-carrier tube 2, said rod 12 comesback onto the axis of said tubular element 13 ₁ and can thus returnfreely to its initial position by moving longitudinally backwards. Saidbaseplate 18 has a second piece 14 for retaining purposes which isL-shaped, having a first plate 14 ₁ and a second plate 14 ₂ at rightangles to the bottom end of said first plate 14 ₁. The top portion ofsaid first plate 14 ₁ presents an orifice of diameter that issignificantly greater than the diameter of the rod 12 and through whichthe rod passes, such that said first plate 14 ₁ can pivot relative tothe axis of the rod 12 under thrust exerted by resilient extender means24 made of elastomer pushing the top portion of said first plate 14 ₁into its position where it slopes towards the rear end of the gun,thereby blocking the rod 12 inside said orifice of said first platebecause of the presence of the resilient extender means 24 which arethen in the compressed position and which seek to return to an initial,expanded position by pushing against the top end of said first plate 14₁, said piece 14 serving to block and retain the rod 12, in particularby preventing it from sliding rearwards in the longitudinal directionwhen said thrust piece 13 returns to its initial position because of thelever arm pivoting upwards. In contrast, said rod 12 slideslongitudinally forwards when said lever arm 10 is pivoted downwards. Theforward sliding of said rod 12 compresses the resilient extender means24, thereby reducing the inclination of said first plate 14 ₁ so thatthe axis of the top orifice of said first plate 14 ₁ moves angularlytowards the axis of the rod 12 and enables the rod 12 to becomeunblocked, allowing it to slide forwards. By exerting upward thrust onsaid second plate 14 ₂, said first plate 14 ₁ is caused to pivot so asto return into a position for unblocking said rod 12, and by compressingthe resilient extender means enables the spear 3 to be uncocked, wherenecessary.

[0080] By moving the moving rod 12 forwards which pushes against themoving piece 11 sliding on the spear-carrier tube 2, the spear is cockedafter operating the lever arm 10 several times, each operation causingthe rod 12 to advance, with the spear being cocked by a plurality ofsuccessive operations on the lever arm.

[0081] Said resilient extender means 24 may be replaced by a mechanicalsystem or by a spring.

[0082] In the figures, the retaining piece 14 is shown as being behindsaid thrust piece 13. Nevertheless, in another embodiment, it ispossible for them to be the other way round, said retaining piece 14being in front of said thrust piece 13, and this can make assemblyeasier.

[0083] Locking means enable the lever arm to be secured to thespear-carrier tube 2 when said lever arm 10 is pivoted towards saidspear-carrier tube 2. The locking means may be constituted by asnap-fastening device 19, 20 comprising two projections 20 mounted ontwo side lugs 19 enabling the spear-carrier tube 2 to be snapped betweensaid side lugs 19.

[0084] Once the operations of cocking the gun has been completed, andthe lever arm 10 is engaged on the tube 2, the bungees 8 are maximallystretched and exert a traction force on the spear 3 along thelongitudinal axis in the forward direction. A plurality of notches 17may be provided along the length of the spear 3 in order to provide aplurality of selectable propulsion forces. Because of the alternatingbracing actions of the thrust piece 13 and the retaining piece 14 hingedon the rod 12 in the baseplate 18, the gun can be cocked without usinggreat force, using a single arm on the lever arm 10.

[0085] The gun can be uncocked without shooting a spear by releasing thebracing effect of the L-shaped piece 14 by applying upward traction onthe second plate 14 ₂.

[0086] In a variant embodiment (not shown), the assembly comprising thespear-carrier tube 2 and the stretching device can be covered by awooden stock: the assembly as received inside the stock is thus hiddenwhich results in an appearance that is more pleasing.

[0087] In another variant embodiment (not shown), said moving head piece11 is fixed on a first element of the spear-carrier tube 2, saidspear-carrier tube 2 being made up of one or more concentric tubeelements that are slidable in one another, with the outer tube elementbeing said first tube element. In this embodiment, the underwater gunthus presents a telescopic spear-carrier tube.

1/ A crossbow-type underwater gun comprising: a butt (1) having amechanism for blocking the rear end of a spear (3) and a member forunblocking said spear, preferably a trigger (4); a longitudinal spearsupport element (2) whose rear end is engaged in said butt (1); andresilient propulsion means comprising at least two bungee type sideresilient cords (8) whose front ends are suitable for being fixed tofixing elements (11 ₁, 11 ₂) and whose rear ends are suitable forengaging in at least one notch (17) in the rear portion of said spear(3); the gun being characterized in that it includes a device forstretching said resilient cords (8), the device comprising: a movinghead piece (11) to which said first fixing elements (11 ₁, 11 ₂) can befixed, said head piece (11) being suitable for sliding along the frontportion of said spear support element (2) between: a rear position (A1)enabling said resilient cords (8) to be engaged without tension in saidnotch (17); and an advanced position (A2) in which said resilient cords(8) are stretched maximally when they are engaged in said notch (17); arod (12), said moving head piece (11) being suitable for sliding alongsaid spear support element (2) by moving said rod (12) in itslongitudinal direction, preferably parallel to that of said longitudinalspear support element (2); and a lever arm (10), said lever arm (10)co-operating with said rod (12) via a thrust and retaining device (13,14, 23, 24) which makes the following possible: moving said rod (12) insaid longitudinal direction under drive from pivoting said lever arm(10); holding said rod (12) in an advanced position corresponding to thetravel distance of said rod (12) resulting from said pivoting of thelever arm (10), while said lever arm (10) is returned to its initialposition (B1) by being pivoted in the opposite direction; and therebyenabling said resilient cords (8) to be stretched by performing asuccession of pivoting operations on said lever arm (10) between aninitial position (B1) and a thrusted position (B2). 2/ A crossbow-typeunderwater gun according to claim 1, characterized in that said leverarm (10) co-operates with a transverse pivot pin (7) secured to saidlongitudinal spear support element (2), thus enabling said lever arm topivot about said pin (7) between: a high initial position (B1) in whichsaid arm is preferably substantially parallel to the rear portion ofsaid longitudinal spear support element (2) and beneath it; and a low,thrusted position (B2) where said lever arm (10) is in an inclined orvertical position. 3/ A crossbow-type underwater gun according to claim1 or claim 2, characterized in that said thrust and retaining devicecomprises: a thrust piece (13) having an orifice through which said rod(12) passes, the orifice being of diameter substantially larger than thediameter of said rod (12) so that said thrust piece (13) can pivotrelative to the axis of said rod (12) between: an off-axis, thrust andblocking position in which said thrust piece (13) is secured to said rod(12) and can entrain it forwards in said longitudinal direction underdrive from pivoting said lever arm (10); and a return position in whichsaid rod (12) lies on the axis of said first orifice, and said thrustpiece (13) can thus return freely to its initial position by movingrearwards in translation in said longitudinal direction; a retainingpiece (14) including an orifice through which said rod (12) passes, theorifice being substantially larger in diameter than said rod (12) suchthat said retaining piece (14) can pivot relative to the axis of the rod(12) between: an off-axis, retaining and blocking position in which saidretaining piece (14) blocks the rod (12) by preventing it from slidingrearwards in said longitudinal direction; and an unblocking position inwhich said rod (12) can slide freely in said longitudinal direction; andsaid retaining piece (14) being held in said retaining and blockingposition while said thrust piece (13) is in its return position, andsaid retaining piece (14) being held in said unblocking position whilesaid rod (12) is sliding forwards in said longitudinal direction. 4/ Acrossbow-type underwater gun according to claims 1 to 3, characterizedin that said lever arm (10) is secured to said thrust piece (13),preferably secured to a plate (13 ₂) of said thrust piece, by means of alink (23) in such a manner that pivoting said lever arm (10) causes saidthrust piece (13) to pivot, said thrust piece (13) occupying: a saidoff-axis, blocking position when said lever arm (10) pivots from itssaid initial position (B1) towards its said thrusted position (B2); anda said return position when said lever arm (10) pivots in the oppositedirection from its said thrusted position towards its said initialposition. 5/ A crossbow-type underwater gun according to any one ofclaims 1 to 4, characterized in that said retaining piece (14) is heldin its said retaining position by resilient extender return means (24),preferably made of elastomer material, suitable for being compressed bypivoting of said retaining piece (14) towards said unblocking position.6/ A crossbow-type underwater gun according to any one of claims 1 to 5,characterized in that said retaining piece (14) is L-shaped having afirst plate (14 ₁) and a second plate (14 ₂) forming a right angle atthe bottom end of said first plate (14 ₁): said orifice of saidretaining piece (14) being in the top portion of said first plate (14₁); said resilient return means (24) being in annular form around saidrod (12) in extension between a stationary stop element (24 ₁) and saidfirst plate (14 ₁); said resilient return means (24) exerting thrust onsaid first plate (14 ₂), pushing it into an inclined positioncorresponding to said retaining position as obtained by blocking saidretaining piece (14), the top end of said first plate (14 ₁) preferablybeing inclined towards the rear of said gun; and said first plate (14 ₁)being capable of being pivoted towards said unblocking position forunblocking said retaining piece (14) by moving said rod (12) forwards insaid longitudinal direction and by pivoting said second plate,preferably upwards, causing said resilient return means (24) to becompressed in both cases so that said spear (3) can be uncocked byexerting upward pressure using a finger on said second plate (14 ₂). 7/A crossbow-type underwater gun according to any one of claims 1 to 6,characterized in that it includes a stationary baseplate (18) secured tosaid longitudinal spear support element (2), said baseplate (18)supporting said transverse pivot pin (7) of said lever arm (10) and thevarious component parts (13, 14, 23, 24) of said thrust and retainingdevice. 8/ A crossbow-type underwater gun according to claim 7,characterized in that said baseplate (18) comprises at least one, andpreferably at least two bottom orifice(s) (29) through which said rod(12) passes, and also preferably at least one top orifice (28) throughwhich said longitudinal spear support element constituting aspear-carrier tube (2) passes. 9/ A crossbow-type underwater gunaccording to any one of claims 1 to 8, characterized in that said movinghead piece (11) has a first orifice (25) through which saidspear-carrier tube (2) passes and a second orifice (26) through whichsaid spear (3) passes and which serves as guide means therefor, and ahollow housing (27) in which said rod (12) comes into abutment to causesaid moving head piece (11) to slide forwards. 10/ A stretching deviceuseful for making a crossbow-type underwater gun according to any one ofclaims 1 to 9, the device being characterized in that it comprises: asaid moving head piece (11) as defined in claim 1 or claim 9; and a saidthrust and retaining piece comprising: a said rod (12) as defined in anyone of claims 1, 3, 6, 8, and 9; a said lever arm (10) as defined inclaims 1, 2, 3, 4, and 7; and preferably a said baseplate (18) asdefined in claim 7 or claim 8 supporting said rod (12) and said leverarm (10) and said thrust piece (13) as defined in any one of claims 1,3, 4, and 7 and said retaining piece (14) as defined in any one ofclaims 1, 3, 5, 6, and 7.